MWACHI:

Aluminum in 2g of an ore sample is determined by dissolving it and then precipitating with Al(OH)3 and igniting to Al2O3, which is weighed. What % of aluminum was in the sample if the ignited precipitate weighed 0.2385g (Al = 27, O = 16, H = 1)?

1 month ago
sillybilly123:

I haven't got the reactions to hand but seems you've ended up with: $$\dfrac{0.2385}{(2 \times 27) + (3 \times 16)}$$ moles of the precipitate $$Al_2 O_3$$ so you had that many moles of Al in the sample, and those moles have mass: $$\dfrac{0.2385}{(2 \times 27) + (3 \times 16)} \times 27 \text{ g}$$ And so the %-age you seek is: $$\dfrac{ \dfrac{0.2385}{(2 \times 27) + (3 \times 16)} \times 27 }{2} \text{ %}$$

1 month ago